Technical Field
The present invention relates to a sheet conveying apparatus, an image forming apparatus, and a sheet post-processing apparatus, and in particular, relates to a sheet conveying apparatus including a conveying path that conveys a sheet and a detecting portion that detects a sheet conveyed on the conveying path, an image forming apparatus including the sheet conveying apparatus and an image forming portion that forms an image on a sheet, and a sheet post-processing apparatus including the sheet conveying apparatus and a post-processing portion that performs post-processing on a sheet.
Description of the Related Art
Conventionally, there have been widely known an image forming apparatus such as a copier, a facsimile, and a complex machine, and a sheet post-processing apparatus to perform a stapling process, a punching process, or the like on sheets on which images are formed by an image forming apparatus. The image forming apparatus and the sheet post-processing apparatus described above incorporates a sheet conveying apparatus that includes a conveying path to convey a sheet and a detecting portion that detects a sheet being conveyed on the conveying path with a sensor.
In general, a conveying path is formed as a space between a pair (e.g., two) of guide members and a plurality of conveying roller pairs are arranged thereon. Such a roller pair is structured with a driving roller and a driven roller. Rotational drive force is transmitted to the driving roller from a power source such as a motor through a gear or a belt. The driven roller is arranged to be contacted to the driving roller.
A detecting portion that detects a sheet being conveyed on the conveying path is arranged at the conveying path. In general, the detecting portion includes a sensor. Various types of sensors exist and are roughly classified into contact type sensors and non-contact type sensors. Typical examples of contact type sensors include lever type sensors and typical examples of non-contact sensors include optical sensors each including a light emitting element and a light receiving element and ultrasonic sensors using ultrasonic.
For example, Japanese Patent Application Laid-open No. 7-221934 discloses a lever type sensor that detects a sheet being conveyed with a lever moved down by being pushed by a sheet. Further, Japanese Patent Application Laid-open No. 2006-64673 discloses a transmission type optical sensor and Japanese Patent Application Laid-open No. 2009-35379 discloses a reflection type optical sensor. Further, Japanese Patent Application Laid-open No. 2005-104682 discloses an ultrasonic sensor that detects a sheet being conveyed using ultrasonic.